Discontinuous wide-angle optic

Abstract

A discontinuous wide-angle optic for use in a light receiver or transmitter comprises a partial spherical element having a planar boundary surface superposed on the base surface of a pyramidal facet reflector provided with a plurality of inclined facet surfaces, one for each of a plurality of directions of incidence of light passing through the spherical surface of said spherical element. When used in a light receiver, the spherical surface functions as a positive lens to cause entering light rays to converge toward one of the facet surfaces of the reflector for reflection therefrom into an image plane located at a diaphragm formed on a surface of said partial spherical element spaced from its said planar boundary surface. A light conductor in the form of a truncated pyramid is provided to limit the field of view, said light conductor being provided with the same number of facet surfaces as the facet reflector and the narrower end of said light conductor being placed in optical contact with said partial spherical element at said diaphragm. A light filter and light detector is disposed adjacent the wider end of the light conductor. When used as a light transmitter, a light emitter is placed adjacent the wider end of the light conductor to cause light to be reflected from the facet surfaces of the light conductor and reflector so as to leave the optic via said spherical surface.

I claim: 
     
       1. A discontinuous wide-angle optic for a light receiver, said optic being located within a space which is bounded by a window structure operative to permit incident light rays to enter said space only in the form of discrete lobes which are oriented respectively at the same angles of incidence relative to a center line in said space, the directions of incidence of said discrete lobes intersecting one another at the same point on said center line in said space, said optic comprising an at least partially spherical element superposed on the base surface of a pyramidal facet reflector having a plurality of inclined facet surfaces, one facet surface for each of the directions of incidence of said discrete lobes, a diaphragm formed on the exterior of said spherical element at a location spaced from the base surface of said reflector, said spherical element and said pyramidal facet reflector each being arranged symmetrically around said center line, said spherical element being positioned in relation to all of the directions of incidence of said discrete lobes to functin as a positive lens for all of said lobes and operative to cause the light rays in each lobe entering said space through said window structure to converge toward one of the facet surfaces of said reflector for reflection therefrom, the inclinations of said facet surfaces being selected to focus said reflected light rays at an image plane located at said diaphragm. 
     
     
       2. The discontinuous wide-angle optic of claim 1 wherein said diaphragm is located on a flat upper surface of said spherical element, said flat upper surface being parallel to said base surface of said pyramidal facet reflector, said flat upper surface being coated with a light-absorbing material from the aperture in said diaphragm outwards towards the edges of said flat upper surface. 
     
     
       3. The discontinuous wide-angle optic of claim 2 including a light conductor, in the form of a truncated pyramid, placed on said upper surface, the narrower end of said light conductor being in optical contact with the uncoated part of said upper surface, whereby the light conductor limits the field of view. 
     
     
       4. The discontinuous wide-angle optic of claim 3 including a light filter disposed adjacent the wider end of said light conductor, said light conductor being provided with the same number of facet surfaces as the facet reflector, each facet surface on the light conductor corresponding to a facet surface on the reflector, the facet surfaces in each such pair of corresponding facet surfaces having an inclination in relation to each other such that light rays reflected from a facet surface of said reflector to pass through said diaphragm thereafter experience a total reflection from the corresponding facet surface of the light conductor and thereafter pass through said filter at the least possible angle to said center line. 
     
     
       5. The discontinuous wide-angle optic of claim 4 including a detector responsive to light passing through said filter operative to indicate if there is an object within the field of view. 
     
     
       6. The discontinuous wide-angle optic of claim 1 wherein said facet reflector is truncated to provide a narrow end surface opposite to said base surface, said narrow end surface including means for fastening the optic within said space. 
     
     
       7. The discontinuous wide-angle optic of claim 4 wherein said wide-angle optic is utilized in a transmitter of light, said light conductor coacting with a light-emitting unit whereby light emitted from said unit is reflected via the facet surfaces of the light conductor and the reflector to leave the optic via the spherical surface of said spherical element.